Lord Carlisle, the former Independent Reviewer of Terrorism Legislation, called for the law to be clarified in order to ensure those guilty of promoting terrorism were held to account.

He said: “This conviction shows the sometimes long march of the law. Whilst those remote from terrorist crime should be prosecuted with caution, there should be greater legal clarity to enable the prosecution of those whose clear aim is to exhort terrorism and the destruction of our way of life.”

Keith Vaz, the Labour chair of the Home Affairs Committee, also said anti-terror legislation ought to be reviewed.

He said: “It is deeply worrying to see the extent of his activities. While congratulating the police in bringing this case to a successful conclusion we now need to look again at the law to ensure that it allows no gaps that permit preachers of hate to undertake their activities under the cloak of freedom of speech exercised in a democracy.

"In future we need to show zero tolerance to those who act and behave in this way.”

Mohammed Rahman was convicted alongside ChoudaryCredit:
PA

British born Choudary and one of his followers, Mohammad Mizanur Rahman, 33, were convicted last month following a four week trial at the Old Bailey.

But details were only made public on Tuesday when a judge lifted reporting restrictions that had been imposed during a similar case featuring some of his associates. He is currently in Belmarsh prison awaiting sentence.

Home Secretary Amber Rudd said: “These dangerous individuals were recruiting sergeants for Daesh. They poisoned the minds of vulnerable people and their warped and twisted propaganda offered support and succour to a murderous and barbaric terrorist organisation.

“The Government is clear. We will continue to confront those who promote hate and threaten our way of life. Together we will protect communities from extremism and defeat this toxic ideology.”

For almost two decades Choudary, as leader of the now banned al-Muhajiroun (ALM) Islamist group, goaded the authorities with inflammatory comments and deliberately provocative statements. He refused to condemn the 7/7 bombings, demanded the imposition of Sharia across Britain and once called for the Queen to wear a burka.

But using his legal training and forensic understanding of terrorism legislation he always managed to stay just right side of the law and avoid prosecution.

Police finally got their chance when they discovered material online in which he praised the murderous Isil regime.

Choudary used social media to promote his extremist views, but during his trial it emerged that companies including Twitter and YouTube had repeatedly refused to remove controversial posts, even after it was arrested.

The father of five, who is a qualified solicitor, could be jailed for up to ten years when he is sentenced next month.

Choudary (centre) on a march in east London in 2008Credit:
Anthony Upton

Choudary's incarceration will also create a headache for the authorities who are desperate to prevent him radicalising other inmates while in prison.

Currently on remand, he will likely be held at Belmarsh maximum security in prison in south east London, which already holds a large number of convicted terrorists.

The prison has previously been described as a “jihadi training camp” but human rights legislation means he can only be held in solitary confinement with the permission of the Justice Secretary.

His conviction was warmly welcomed by Scotland Yard last night, who believe Choudary can be linked in some way every major terror plot unearthed in this country in recent years.

However his influence has also been felt further afield with jihadists in other countries, including France and Belgium being inspired by his online rantings and through links to ALM.

Commander Dean Haydon, head of the Met’s counter terrorism command described Choudary as a “very dangerous and clever individual” who had played a key role in recruiting some of the 850 Britons who are currently fighting for Isil.

He said: “These men have stayed just within the law for many years, but there is no one within the counter terrorism world that has any doubts of the influence that they have had, the hate they have spread and the people that they have encouraged to join terrorist organisations.

“Over and over again we have seen people on trial for the most serious offences who have attended lectures or speeches given by these men.

He added: “You can go back over history and find an awful lot of terrorists linked to ALM, Islamic State or both. 7/7, Lee Rigby, there was a whole host of other cases which are linked back to ALM and Islamic State.”

Choudary led the now banned al Muhajiroun groupCredit:
Ian Jones

Describing how he had finally been brought to justice, Commander Haydon said: “His mistake was pledging an oath of allegiance. That was the key piece of evidence that tipped him over the line for a terrorist offence.”

Former Metropolitan Police anti-terror officer David Vidicette said: "This conviction is very good news for the police, the security services and the country.

"Every time the police investigated a plot he was either directly linked or only a hop away and it has taken far too long to bring him to justice."

Anti-terror cops examined 20-years’ worth of material following his arrest in September 2014 before charging Choudary and Rahman in August last year.